Tanzawa Mountains Research Articles

Use of a young plantation by sika deer (Cervus nippon TEMMINCK) in the Tanzawa Mountains

Use of a young plantation by sika deer (Cervus nippon TEMMINCK) in the Tanzawa Mountains

Leaching of cell wall components caused by acid deposition on fir needles and trees

Virgin fir forests have been declining since the 1960s at Mt. Oyama, which is located at the eastern edge of the Tanzawa Mountains and adjacent to the Kanto plain in Japan. An acid fog frequently occurs in the mountains. We collected throughfall and stemflow under fir trees and rainfall every week during January–December 2004 at Mt. Oyama to clarify the influence of acid fog on the decline of fir ( Abies firma) needles. In relation to throughfall and stemflow, d-mannose, d-galactose, and d-glucose are the major neutral sugar components; only d-glucose is a major component of rainfall. The correlation coefficient between the total neutral sugars and uronic acid (as d-galacturonic acid), which is a key component of the cross-linking between pectic polysaccharides, was high except for rainfall. The leached amount of calcium ion, neutral sugars, uronic acid, and boron is related to the nitrate ion concentration in throughfall. Results of a laboratory exposure experiment using artificial fog water simulating the average composition of fog water observed at Mt. Oyama (simulated acid fog: SAF) on the fir seedling needles also shows a large leaching of these components from the cell walls of fir needles. The leaching amount increased concomitantly with decreasing pH of the SAF solution. We also observed that a dimeric rhamnogalacturonan II-borate complex (dRG-II-B) that exists in the cell wall as pectic polysaccharide was converted to monomeric RG-II (mRG-II) by the leaching of calcium ion and boron. Results not only of field observations but also those of laboratory experiments indicate a large effect of acid depositions on fir needles.

Postcollisional exhumation history of the Tanzawa Tonalite Complex, inferred from (U‐Th)/He thermochronology and fission track analysis

The Tanzawa Mountains in the South Fossa Magna region, in the middle of the Japan Arc, were formed due to collision of the Izu‐Bonin Arc against the Japan Arc during the last several million years. The Tanzawa Tonalite Complex is exposed in the Tanzawa Mountains and is inferred to represent middle crust of the Izu‐Bonin Arc. We performed new thermochronometry, consisting of (U‐Th)/He dating, fission track dating, and fission track length analysis for the complex to investigate the exhumation history of the Tanzawa Tonalite Complex caused by arc‐arc collision. Typical (U‐Th)/He ages were 2.0 ± 0.2 Ma on apatite, 3.3 ± 0.2 Ma on zircon, and 4.5 to 6.9 Ma on zircon using the fission track method. The mean fission track length was 9.7 ± 0.6 μm (2 SE). The cooling rate of the tonalite has been calculated to be in the range of 20°–60°C Ma−1 from ∼7 to 3.3 Ma, ∼80°C Ma−1 from 3.3 to 2.0 Ma, and ∼30°C Ma−1 from 2.0 to 0 Ma assuming a surface temperature of 10°C. The exhumation rate has been calculated to be 0.5 to 1.5 mm a−1 from ∼7 to 3.3 Ma, ∼2 mm a−1 from 3.3 to 2.0 Ma, and ∼0.8 mm a−1 from 2.0 to 0 Ma with an assumed geothermal gradient of 40°C km−1. The exhumation rate has not changed significantly despite the simultaneous tectonic changes around the Tanzawa Mountains after ∼7 Ma.

Effects of Hiking Trails for Vegetation on the Tanzawa Mountains, Kanagawa Prefecture, Central Japan

Effects of Hiking Trails for Vegetation on the Tanzawa Mountains, Kanagawa Prefecture, Central Japan

Formation Mechanism of a Low-Level Jet during the Passage of Typhoon Ma-on (2004) over the Southern Kanto District

On 9 October 2004, Typhoon Ma-on hit the southern Kanto district in eastern Japan. Strong winds were observed in the left-rear quadrant of Ma-on near the typhoon center during its passage over the southern Kanto district in spite of the rapid translation speed of about 70 km h-1. Numerical simulations of Ma-on were performed using a nonhydrostatic model with a horizontal grid spacing of 2 km. The simulation results showed that the strong winds on the left-rear quadrant of Ma-on were low-level phenomena after landfall. The low-level jet (LLJ) associated with the observed strong winds formed over the Sagami bay just after the typhoon center had passed. The typhoon moved over the pre-existing low-level cold air in the Kanto region. When the typhoon center reached the Sagami bay, the northerly flow of the low-level cold air formed a narrowed channel between the typhoon center and the Kanto Mountains in the west of the Kanto plain. The LLJ corresponded to the outflow response from the narrowed channel to the Sagami bay. Trajectory analysis illustrated that the parcels which passed through the LLJ traveled southward parallel to the Kanto Mountains. When they passed near the Tanzawa Mountains at the southern tip of the Kanto Mountains, significant subsidence, spreading and acceleration occurred toward the Sagami bay. The horizontal momentum budget analysis and diagnostic evaluation of pressure gradient force (PGF) revealed that the LLJ was mainly supported by the large-scale southward PGF due to Ma-on. However, locally generated mesoscale forcing due to the decreasing depth of cold layer worked around the exit of the narrowed channel of the cold air. Thus, we conclude that the dynamics and structure of the LLJ were close to those ofgap wind. The sensitivity experiments showed that the low-level cold air as well as the relative position between the high mountainous topography and the typhoon was essential for the LLJ formation.

丹沢産微小菌類： 分生子柄束形成菌類ならびに関連菌 (1)

丹沢産微小菌類： 分生子柄束形成菌類ならびに関連菌 (1)

Preliminary Study on Evaluation of Effects of Acid Deposition on Forested Ecosystem in East Tanzawa Mountains Estimated from Chemical Characteristics of Stream Waters

It has been reported that the nitrate concentration in stream water in the mountainside on Mt. Oyama (1252 m a.s.l), which is located at the western part of Kanagawa Prefecture, is higher than that in stream water in other regions, indicating that nitrogen saturation is occurring in the forested ecosystem. However, there has been no report on nitrogen saturation across the Tanzawa mountains, except Mt. Oyama. We investigated the current status of the stream water chemistry and the effect of acid deposition on the stream water chemistry across the East Tanzawa mountains. Thirty-eight samples were collected in nine mountain streams in this region. The mean pH and alkalinity in stream water in this region were 7.315 and 650 μeq/L, respectively. There was no symptom of stream-water acidification by acid deposition in East Tanzawa, probably because of the high acid buffering capacity by the weathering of carbonate and silicate minerals. Nitrate concentrations in the stream water ranged from 27.6 to 87.8 μeq/L and NH4+ was detected. High nitrate concentration in stream water suggests that nitrogen saturation is occurring in the forested ecosystem in East Tanzawa mountains. We divided our sampling sites into southeast (SE), southwest (SW), and north (N) regions by the ridge line of Mt. Tanzawa - Mt. Tonodake - Shindainichi - Mt. Sannoto - Mt. Takenodai - Mt. Oyama - Mt. Mitsumine. The stream water pH was lower and the concentrations of Na+ and NO3− were higher in south regions. There were high correlations between the concentrations of Na+ (r = −0.854), Cl− (r = −0.815) and NO3− (r = −0.922) and the distance from the coast of Odawara City, Oisomachi, and Ninomiyamachi. In addition, a high correlation between the NO3− and Cl− concentrations (r = 0.741), which is an indicator of atmospheric deposition, in stream water was observed. Our preliminary investigation indicates that the runoff of nitrate, originated from atmospheric deposition, might occur in the forested ecosystem in the southern regions in East Tanzawa.

Study of dung beetles in feces of sika deer, Cervus nippon, in Tanzawa Mountains, central Japan

Study of dung beetles in feces of sika deer, Cervus nippon, in Tanzawa Mountains, central Japan

Seasonal Change of Bats Using Tunnels as Roost in Kurokura Basin of the Tanzawa Mountains, Kanagawa Prefecture

Seasonal Change of Bats Using Tunnels as Roost in Kurokura Basin of the Tanzawa Mountains, Kanagawa Prefecture

Morphological, genetic and behavioural analyses of a hybrid zone between the ground beetles Carabus lewisianus and C. albrechti (Coleoptera, Carabidae): asymmetrical introgression caused by movement of the zone?

We analysed the putative hybrid zone between the ground beetles Carabus lewisianus Breuning and C. albrechti Morawitz from the Kanto and Tanzawa Mountains in central Honshu, Japan, using morphological, genetic, and behavioural data. Canonical discriminant analysis of three external and five genital morphological characters revealed an apparent morphological gap, suggesting restricted sympatry in the contact zone. RFLP and molecular phylogenetic analyses of the mitochondrial gene ND5 revealed that haplotypes originating from C. lewisianus introgressed extensively into C. albrechti. Fitting tanh curves to morphological (external and genital) and genetic characters showed differential cline widths and centres, suggesting stronger selection for genital morphology with narrower cline widths, and extensive introgression of the nuclear genes responsible for external characters relative to those controlling genital morphology into the range of C. albrechti. Linkage disequilibria between the morphological characters did not differ from zero, suggesting sufficient recombination occurred in the zone but the effect of small sample sizes was not negligible. Mate choice trials demonstrated that males showed a weak but not significant preference for conspecific mates. We interpret these patterns as evidence for (1) partial reproductive isolation presumably by postmating processes; (2) selection against intermediate genital morphologies, and (3) independent responses of the characters to different evolutionary forces that may cause movement of genital clines and introgression of the mitochondrial gene and external morphology. The movement of the boundaries may have resulted in the particular species distribution patterns in the study area. © 2005 The Linnean Society of London, Biological Journal of the Linnean Society, 2005, 86, 79–94.

Demographic genetics of Siebold's beech (Fagaceae, Fagus crenata Blume) populations in the Tanzawa Mountains, central Honshu, Japan. II. Spatial differentiation and estimation of immigration rates using a stepping‐stone structure

AbstractThe spatial genetic substructuring of five local populations of Siebold's beech (Fagus crenata Blume) in the western Tanzawa Mountains were analyzed using allozyme polymorphisms for 13 loci (11 enzyme systems). The beech forests in Tanzawa have been rapidly deteriorating in recent years. The two main causes for this are heavy damage or death of mature trees caused by air pollution, and feeding pressure on seedlings and juveniles by sika deer. The distributions of genotypes showed localization of particular genetic diversities. Spatial autocorrelation analyses revealed slightly positive significant values within small distance classes and negative values in further distance classes, but those values more or less fluctuated in the distrograms. In addition, an analysis was conducted using a stepping‐stone model to estimate the migration rate and to quantify the gene flow among neighboring patch populations to detect the population differentiation. Twelve patch populations were discriminated as localized assemblages of Siebold's beech individuals in one of the local populations according to the assemblage of individuals along the topography of an established site. The migration rate for each generation was estimated to be m = 0.09 between neighboring patch populations. The population migration rate (Nm = 2.7) was revealed to be larger than one migrant for every other generation, which indicates that the population differentiation is not significant in the present state. Although the model analysis demonstrated sufficient gene flow between neighboring patch populations, severe damage to local beech populations in Tanzawa may cause the extinction of one or more of the patch populations. Further fragmentation and isolation of local populations were also discussed in terms of loss and retreat of genetic diversity.

Influences of Forest Decline on Various Properties of Soils at Mt. Hirugatake, Tanzawa Mountains, Kanto District, Japan

At Mt. Hirugatake in the Tanzawa Mountains, Kanto district, Japan, the deciduous broadleaved forests have rapidly declined. In our previous studies, we reported that the amount of soil organic matter had significantly decreased at the early and final stages of forest decline, and that the soil microbial biomass also showed a large decrease at these stages, suggesting that the composition of soil organic matter might have also changed with forest decline. To clarify the influences of forest decline on the composition of soil organic matter, the amount of humic substances, optical properties of humic acid, and the amount of soil carbohydrates in surface soils at different stages of forest decline were investigated. The amounts of humic acid and fulvic acid decreased to a lesser extent at the early and middle stages of forest decline, and showed a significant decrease at the final stage. As the amount of humin significantly decreased at the early stage, it was plausible that the distinct decrease in the total carbon content of the soil surface horizons at the early stage of forest decline was induced by the decrease in the amount of humin, and at the final stage, by the decrease in the amounts of humic acid and fulvic acid. The amount of soil carbohydrates did not change appreciably with forest decline although the soil organic matter content markedly decreased. It was suggested that most of the carbohydrates in the soil surface horizons were in a stabilized form consisting of complexes with humic substances, metals, and minerals, and would not be affected by the environmental changes associated with forest decline.

Results of forty-six year monitoring of landslides in Nakatsu River basin in Tanzawa Mountains

Results of forty-six year monitoring of landslides in Nakatsu River basin in Tanzawa Mountains

Protection of endangered plants from sika deer herbivory using deer-proof fences in the Tanzawa Mountains, central Japan

Protection of endangered plants from sika deer herbivory using deer-proof fences in the Tanzawa Mountains, central Japan

Home Range Characteristic of Sika Deer in Fudakake of Tanzawa Mountains

Home Range Characteristic of Sika Deer in Fudakake of Tanzawa Mountains

Influences of forest decline on various properties of soils on Mt. Hirugatake, Tanzawa Mountains, Kanto District, Japan

At Mt. Hirugatake, Tanzawa Mountains, the deciduous broadleaved forest has declined rapidly since the 1970s. Six study sites under different degrees of forest decline were selected at Mt. Hirugatake, Tanzawa Mountains as follows: site with healthy deciduous broadleaved forest (DBF), site with slight forest decline (SFD), site with distinct forest decline (DFD), sites with heavy forest decline 1 and 2 (HD1 and HD2), and site with Sasa-type grassland (SG). In the present study, the changes in the physical and chemical properties of the surface soil to the depth of 10 cm with that order of forest decline were investigated in nine sub-samples from each quadrat (10 m × 10 m) at each site. With forest decline, the bulk density tended to increase, and porosity, especially macropores, tended to decrease significantly. Although the soil pH decreased at the SFD site, no significant differences were found in the soil pH between the DBF site and the other sites. The amount of exchangeable aluminum was well correlated with the soil pH, but showed no significant differences between the DBF site and other sites, except for the SFD site. Thus, forest decline at Mt. Hirugatake, Tanzawa Mountains was not caused by aluminum stress, as suggested in the previous study (Higashi et al.: Soil. Sci. Plant Nutr., 49, 161'169, 2003). The amount of total carbon of soils markedly decreased at the early and the latest stages of forest decline; a decrease of about 34% was observed at the SG site compared with the DBF site.

Influences of forest decline on various properties of soils on Mt. Hirugatake, Tanzawa Mountains, Kanto District, Japan

To evaluate the influences of forest decline on microbial properties, the biomass carbon content and the activities of several enzymes in surface soils under different degrees of forest decline at Mt. Hirugatake, Tanzawa Mountains, Kanto district, Japan were investigated. The biomass carbon content as well as the activities of the dehydrogenase, β-glucosidase, and protease enzymes was significantly decreased with forest decline, and the correlation analysis suggested that these decreases were caused by the decrease in the soil organic matter content associated with forest decline. Moreover, the changes in the composition of soil organic matter might exert a significant influence on the microbial properties, since the proportions of the decrease in the biomass carbon content and enzyme activities were higher than those of the decrease in the total carbon content when a healthy forest site and other five sites with forest decline were compared. Furthermore, stepwise multiple regression analysis strongly indicated that the microbial properties were also affected by the changes in the water-holding capacity and porosity of the soils associated with forest decline in the study area.

Influences of forest decline on various properties of soils on Mt. Hirugatake, Tanzawa Mountains, Kanto District, Japan

To investigate the changes in the vegetation, soil profile morphology, and some chemical properties of the soils under different conditions of forest decline, six representative study sites were set up on Mt. Hirugatake, Tanzawa Mountains, Kanto district, Japan, where serious forest decline had been observed since the 1970s for broadleaved deciduous trees. The selection of the study sites under different degrees of forest decline was based on the interpretation of vegetation changes in aerial photographs taken in 1947, 1967, 1977, and 1993, and also on vegetation surveys at and around the selected sites. The results obtained were as follows. The soil profile morphology was similar among the study sites in terms of depth, sequence, and content of scoria fragments in each horizon. However, with the disappearance of tree layers of Fagus crenata and associated trees, the thickness of the O horizon had decreased and the distribution of medium to coarse roots had also decreased, especially at the advanced stage of forest decline. The increase in the hardness of the surface soils and the decrease in the soil organic matter content tended to occur at the very early stage of forest decline. As for the changes in the chemical properties of the soil samples associated with forest decline, the pH and contents of exchangeable bases did not show a definite tendency while the content of exchangeable AI seemed to decrease, especially for the A horizon. Accordingly, it is unlikely that the acidification of soils was the major factor responsible for forest decline in the study area, in contrast to the results obtained in investigations of forest decline areas conducted in Europe.

Hiking trail erosion in the Southern part of the Tanzawa mountains

Hiking trail erosion in the Southern part of the Tanzawa mountains

Nutritional evaluation of forage for sika deer in the eastern part of the Tanzawa Mountains, Japan: a preliminary study using the rumen fluid of sheep

Nutritional evaluation of forage for sika deer in the eastern part of the Tanzawa Mountains, Japan: a preliminary study using the rumen fluid of sheep